The present invention relates generally to apparatus and methods for treating vascular conditions, and more specifically, to a balloon-stent combination that treats the vascular condition and leaves at least a portion of the balloon inside the vessel after treatment.
Atherosclerosis and other occlusive diseases are prevalent among a significant portion of the population. In such diseases, atherosclerotic plaque forms within the walls of the vessel and blocks or restricts blood flow through the vessel. Atherosclerosis commonly affects the coronary arteries, the aorta, the iliofemoral arteries and the carotid arteries. Several serious conditions may result from the restricted blood flow, such as ischemic events.
Various procedures are known for treating stenoses in the arterial vasculature, such as the use of atherectomy devices, balloon angioplasty and stenting. During an atherectomy procedure, vascular plaque may be removed by inserting a catheter having a rotating cutting blade into the vessel and using the blade to shave away the plaque. During a balloon angioplasty procedure, a catheter having a deflated balloon attached thereto is positioned across a constricting lesion, and the balloon is then inflated to widen the lumen to partially or fully restore patency to the vessel.
Stenting involves the insertion of a usually tubular member into a vessel, and may be used alone or in conjunction with an angioplasty procedure. Stents may be self-expanding or balloon expandable. Self-expanding stents typically are delivered into a vessel within a delivery sheath, which constrains the stent prior to deployment. When the delivery sheath is retracted, the stent is allowed to radially expand to its predetermined shape. If the stent is balloon expandable, the stent typically is loaded onto a balloon of a catheter, inserted into a vessel, and the balloon is inflated to radially expand the stent.
Many recent self-expanding and balloon expandable stents have been coated using various agents, such as drugs or bioactive materials, to achieve a biological effect in addition to applying a radially outward force. Such drug coated stents may deliver the agents in close proximity to a stenotic lesion to reduce the likelihood of restenosis.
One problem frequently encountered with atherectomy, angioplasty and stenting procedures is that pieces of plaque are often dislodged from the stenosis. Such pieces of plaque, referred to as emboli, may flow away from the stenosis into other areas of the vasculature and may be difficult to retrieve. Serious complications, such as heart attack and stroke, may occur where the emboli travel into the coronary or carotid arteries.
Several techniques exist for retrieving emboli during a medical procedure, such as deploying a filter within the vasculature distal to the stenosis. However, an important consideration is reducing the amount of emboli that becomes dislodged into the vasculature, and many filters may compound the problem by dislodging plaque as the filter traverses the stenosis. There is a need for apparatus and methods that effectively treat a vascular condition by restoring patency to the vessel while reducing the likelihood that emboli becomes dislodged into the bloodstream.